The invention relates to the field of providing a three-dimensional co-registration between intravascular and angiographic data.
For quantification of the build-up of atherosclerotic plaques in blood vessels and therapy planning, x-ray projections are acquired with injection of contrast agent into the appertaining vessel in a catheter laboratory and analyzed two-dimensionally or possibly three-dimensionally. In some cases, an intravascular imaging (for example, optical coherence tomography (OCT) or intravascular ultrasound (IVUS)) is also referenced in order to obtain further information about the morphology and other properties of the plaque.
When OCT or IVUS images are acquired using the “pullback” method, x-ray projections are also simultaneously acquired in order to check the position of the tip of the OCT or IVUS catheter in real time. The problem is that, in this method, the images are stored on separate platforms such that afterwards a temporal association/registration is no longer possible. Given a review of the images, the user is therewith no longer in the position to recognize which OCT or IVUS image shows which point in the vessel.
In practice, doctors look for anatomical landmarks (for example, bifurcations or a number of side branches) that can be recognized both on the x-ray projections and on the intravascular images and thus orient themselves in the vessel. However, this is a very involved, time-consuming, and imprecise method.
A solution to this problem is disclosed in Dagres, Haude Kurreck, Bamugart and Erbel, “The EchoMap system: online integration of intracoronary ultrasound and procedure parameters”, Journal of Interventional Cardiology, Vol. 17, No. 5, 2004, that goes by the name of EchoMap in connection with an IVUS apparatus. EchoMap offers a picture-in-picture representation of IVUS images and x-ray projections during an IVUS withdrawal. After the pullback, the complete scene of the picture-in-picture scene can be stored. The disadvantage of this method is that the IVUS images or x-ray projections cannot be processed in the picture-in-picture representation. Moreover, a region of the x-ray projections is not visible (since it is covered with the IVUS image) and the IVUS images are shown very small.